Keep in mind that if you're looking for a narrow seat for the purposes of fitting more than one car seat in a car, then it's not always the overall width of the seat that is the be-all-and-end-all of whether or not a seat will fit. Rather, if the seats you're working with "puzzle" together with each other, you might be able to fit (for instance) 55" of child seat into 50" of vehicle seat.